The Foursquare Hello Facebook Android Sample Code by Foursquare demonstrates how to interact with Facebook. After practice, developers can create a real world application that can notify a user if a photo has been uploaded.
Foursquare, the leading location-based social tool, announced a major new initiative last week to expand its location database to include cross-references to corresponding venue listings from other services. As characterized in the announcement post on the company blog, the goal is to make Foursquare the missing "Rosetta Stone for location, allowing you to link information about a real-world place from one database to any other." Now it's not just about using Foursquare, but connecting it to other services.